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Why bother going green?

By Fred Pearce

PLENTY of people say it, and the rest of us probably think it as we browse the energy-efficient light bulbs, unplug our TV or leave the car and walk to the shops instead. What’s the point in cutting our personal carbon footprint when more than a billion Chinese and most of the rest of the planet are jacking up their emissions as if there were no tomorrow?

It’s a fair question. After all, the atmosphere doesn’t distinguish between a tonne of Chinese carbon dioxide and a tonne emitted by the west. As the rest of the world carries on regardless, are the paltry savings from recycling your beer cans or insulating your roof anything more than a drop in the ocean? If you just stopped trying, would the planet notice? In this special investigation, we crunch the numbers to find out whether going green is worth all the bother.

First though, the big picture. Every year human activities add about 30 billion tonnes of CO2 to the atmosphere, largely through burning fossil fuels but also through destroying natural carbon sinks, such as forests. Half of this CO2 is absorbed by the remaining forests, soils and oceans, but the rest accumulates in the atmosphere.

Since pre-industrial times, the concentration of CO2 in the air has risen by a little over one-third, from 270 parts per million to 380 ppm – or from 2.2 trillion tonnes to almost 3 trillion. Most scientists think it would be unsafe to let CO2 concentrations rise beyond 450 ppm – an additional 500 billion tonnes. That level would be …